Emiah eugene mathewson



B. O. TILGHMAN & J. E. MATHEWSON. ART OF SHARPENING FILES AND OTHER SIMILARLY TOOTHBD TOOLS.

No. 252,979. Patented Jan. 31,1882.

- Fig.1,

NMED STATES V ATENT ()rrrcn,

.lllthlJAll-Illfl o. TILGIIMAN AND JEREMIAH icylimrnnwson, or PHILADEL- rum, PA.; SAID MAT-HEWSON ASSIGNOR Lro SAID TILGIIMAN.

ART OF Sl'lllRlENlilG FILES AND OTHER SlMlLARLY-TOOTHED TOOLS.

srncrmce'rron forming m of Letters Patent No. 252,979, dated January 31, 1882.

Application filed May 12, 1819.

To all whom it may concern: 1

Be it known that we, BENJAMIN CHEW TILGII- MAN, of Philadelphia, Pennsylvania, and JER- EMIAH EUGENE MA'rnnwsoN, of the same place, have in vented certain Improvements in the Art of Slmrpening-Files, Itasps, Saws, and similar toothed tools, either straight or circular, by the sand-blast; and we do hereby dcclare thautlie following is a full and-exact description thereof.

Out; invention relates to the sharpening of files, rasps, and similar toothed tools by the sand blast, as described in the patent of Milo A. Richardson, dated January 22, 1878.No. 199,573, and in the patentof said I (l. Tilghman, dated Uctober 18, 1870, No. 108,408.

Herein we will call the stream of sand im-.

polled by the jet of steam, air, &c the sandblast and the system of tubes used to pro does it the blast-pipe.

Heretofore in sharpening files, &c., the sand- =blast has been applied in a round stream produced by a blast-pipe composed of two concentric tubes, the inner tube supplying the sand, while the steam was supplied by the annular aperture between the two tubes, in

Y the manner described. in said 'lilghmans Pat-- cut No. 108,408. The files have been moved lengthwise under the sand-blast, and when they are wider than the sand-blast a lateral motion is also given, so as to expose all parts in succession to the action. 'these movements have been given sometimes by hand, sometimes by suitable machinery;

In practice there-are certain inconveniences in the above methods. As the sand employed is of such very fine grain that it would not run equably in a dry state, itis generally used mixed with water, in the state of a fluid mud. This mud moves so sluggishly under the influence of the suction or partial vacuum produced'by the steam-jet that a central tube of any convcnient size, such as would be ample for the supply of dry sand, will not supply a sutliciehtquantity ofthe fluid mud. We have found sharpening actionot' the sand blast is thus blast with another.

to supply the steam made more rapidand efiicient than when the fluid mud is supplied in the center and the steam outside.

We should remark that there is an objection to increasing the diameter of the tubes forming a round sand-blast to be used in sharpening files, because, as the sand-blast is applied at an acute angle with the surface, the steam and sand which strike the part'of the file nearest to the nozzle-tube are glanced oil, and must necessarily pass through and to some extent interfere with the steam and sand which strike the file farther ofi. The greater the diameter of the round stream the greater will be this interfering action of one portion of the sand- Also. when a file is held and moved by hand under a round sand-blast it is difficult to regulate the lateral motion so as to produce an equal effect upon all parts. in operating on the wide face of a flat-file, as soon as the edge of the face is brought under the blast the forccacts upon the vertical side of the file and tends to shove it suddenly sidewisc, away from and out' of the blast; and the result is that it is likely to receive too much grinding in the center of the flat faces, and not enough at the edges, and its surface is apt to become somewhat hollow, which makes it work badly. If the movements of the file under the sand-blast aresuitablyregulated by machinery, these difficulties may to some extent be avoid ed, but'other inconveniences are then incurred. \Ve have found that it is an improvement to use a sand-blast which is wide in the direction of the width of the file and thin in the direction of the length of the file, and that in this way the whole width of a file can be acted upon simultaneously and in a more'equable manner, and without the necessity of lateral motion, and also that the interfering action above referred to is much less. l In ourimproved wide and thin sand-blast we have sometimes introduced the steam by oneor more thin openings situated in the same plane and the fluid mud by another Wide and thin parallel opening; but we prefer to introholes placed in a row side] by side "a littledistance apart, so that the fluid mud, thoughit maybe introduced onlyfrom one side, is drawn duce the steam by a numberof small round I in by the suction between and around the separate jets of steam, all of which blow into the same nozzle-tube of a suitable wide and thin aperture or cross-section corresponding to the size and number of the steam-holes. The sand or fluid mud thus gets more evenly distributed and better mixed with the propelling-steam. By increasing the number of the steam-holes placed side by side' we can make this compound or multi-holed blast-pipe of any desired width,

so as to operate at once on the entire width ofthe widest file, while the sand-blast still remains thin in the direction of the length ofthe file.

It should be observed that a stream of sand impelled by a single round jet of steam, and striking at an acute angle on the flat surface of the file, must naturally tend to produce a rounded groove. By our improvement of a number of small steam-holes in a row, sucking the sand between them and blowing it into the same wide and flat nozzle-tube, the separate streams diverge sidewise into each other and form one wide and thin sand-blast, which has much less tendency to make the surface of the file hollow or concave.

The kind offile mostin use is of a.- fiat shape, with teeth on one or both of its narrow sides.

Heretofore it has been the practice to use at the same time two blast-pipes, one pointing upward and the other downward, at the proper angles in the same vertical plane, so that by moving the file horizontally lengthwise and sidewise between these blast-pipes its two opposite surfaces are acted upon simultaneously, and afterward the other two surfaces are operated on in like manner. Itthus took nearly as long to sharpen the two narrow sides as the two wide ones.

We have found that it is an improvement to use thin sand-blasts considerably wider than the files treated, and to arrange two of them so that the upper one inclines downward'and to one side, (say to the left, while the lower one inclines upward and to the other side, (say to the right,) andto cause the file to be moved horizontally lengthwise between them, so as to present its opposite sides at equal angles to the two sand-blasts, and that in this way all the four sides of the file may be-sharpeued simultaneously.

-We find it convenient to make the sandblasts each about one-half to three-fourths of an inch wider than the file, and to give to the upper one an inclination downward of about twenty-five degrees, and an inclination to the left of about eleven degrees,and to give to the lower one inclinations at similar angles upward and to the right.

Thedistance between the ends of the nozzletubes will depend on the thickness of the files treated for files about three-eighths of an inch thick about one and a quarter inch from center to center of the ends of the nozzle-tubes is convenient. Even when round sand-blasts are used it is an improvement to direct them' at call herein the feeler.

quently resharpened, it is very desirable that the workman should possess some means of knowing accurately at each instant of the operation the effect produced on the file, and also the condition of every part of its surface, so that he can expose it to the sand-blast at the proper places and for the proper time. Our improved device for this purpose is to use a bar of metal, (generally gun-metal,) which we will When the working is done by hand this is secured to one of the blast-pipes in such a manner that as the workman moves the file under the blast he can keep it slightly pressed against the feeler. At first, while the file is dull, it slides easily on the feeler, but as the sharpening progresses the workman perceives that it begins to bite more and more, and by thus testing its whole length and each side he can judge when it is well sharpened in all parts.

The nozzle-tube, in which the sand becomes mixed with the steam and gains velocity from it, is the part of the apparatus which wears out most rapidly, and it is desirable that it should be cheap and easily renewable. The best materiatis white cast-iron; but it is diflicult to make a sound castin got a tube having an aperture only about three-sixteenths of an inch wide, such as is suitable for our wide and thin sand=blasts. We cast the nozzle-tube in two separate pieces or. half-tubes, which, when put together, form a tube, and are held together and in place by a clamp, the joints being made tight with red lead or putty.

For good working it is desirable that the supply of fiuid mud should be of abouta uniform degree of thickness or proportion of solid matter. In an ordinary tube or box the tendency of the solid matter to settle to the bottom is apt to cause irregularity, unless the mixture is frequently stirred. Our improvement is to make the mud-vessel of the shape of a cone standing on its point, and to draw the supply of mud from its bottom. As the horizontal area of this vessel decreases toward the bottom. the current is proportionately more rapid, and we find that the supply of mud is thus made more regular and the suction-tubes,

are less apt to become choked, since the mud is always drawn from the point where it is? thickest and no sedimentary deposit can have .time to form, and thereby alter the rate of cutting-of the apparatus.

The following is a description of the appsratus which we prefer to use in order to carry of about sixty pounds pressure per square inch.

b is a separate piece of gun-metal, which is to be fastened by screws to a, the joint being made tight by solder or otherwise. In I) are bored the steam-holes c 0, about one-fourth of an inch apart from center to center, and about sixteen one-humlrcdths of an inch in diameter at their front or small end, and continuing of this diameter backward for about onesixth of an inch, and then widening conically until their edges meet. The central lines of these steam-holes should bcparallcl tothe central line of the screwy. The projecting part d of the piece b has its upper surface made parallel with the axes of the holes 0 c.

g g is the nozzle-tube, made preferably of very hard cast-iron; It is made in two pieces, which, when put together, form a fiat tube about-two and a halt inches long, and having a wide and thinaperture, the cross-section of which is about tlu'ee-sixteenths 2,) of an inch high, and about one-quarter of an inch wider than the row of steam-holes. The nozzle-tube g is held together and also fastened to the piece b d by the clamp When necessary, packing-pieces of thin metal or paper are inserted between the nozzle-tube and the piece (I, so as to insure that the central plane of the nozzletubc shall coincide with the centrallinesof the steam-holes c c. This adjustmentis important, if itis not accurate the sand-blast will strike too much upon either the upper or lower side of the nozzle-tube and will soon out it away.

In order to admit the supply of fluid mud, the lower half of the nozzle-tnbeggis cut away for about oneeighth of an inch at its inner end, 0, and a corresponding aperture, 'v, is made in the piece d, so as to communicate with the cross-tube'o and the vertical pipe f, which descends to the bottom of the conical mud-vessel 1), Fig. 4. The metal of the piece I; d is also sloped ofi' below the row of steam-holes, so as to facilitate the entrance of the fluid mud from the tube o'into thenozzle-tuhe. All the joints between and around the nozzle-tube are made air-tight with red lead or putty.

Fig. 3 shows in cross-section and full size the two pieces composing the nozzlctube g g, and also shows the steam-holes cc, as seen by looking'into the end of the nozzle-tube.

Fig. a shows in quarter-size the method of mounting the apparatus for use.

.9 isthe settling-chamber in which the fluid mud is collected after being used. It consists of a wooden box about six feet cnbe,havinga sloping water-tight bottom with a gutter in the middle.

t is the working-hole, about four inches long by two and a half inches high, in the front of the chamber s. The two converging blastpipes or a. drive through this hole into thechamher a the streams of fluid mud and steam, together with a current of air. The mud and water fall to the bottom and return by the gutter to the-conical mud-vessel p, from which it is again sucked up by the tubes ff into the blast-pipes and reused. The waste steam and air escape to a chimney by a hole about one foot square in the top of the chamber 8.

mm, Fig. 4, show the feeler. which is geuerallyabarof gun-metal aboutone and a quarter inch wide, one-quarter of an inch thick, and of any convenient length. It is fastened on top of the lower blast-pipe and projects beyond the end of the nozzle-tube, so that; whena tile, k,is laid horizontally upon the proiecting end of the feeler the opposite surfaces of the file will be at about equal distances and angles from the ends of the two nozzle-tubes. As the projectingend of the-feeler gets worn away by the rubbing of the file it is pushed forward.

The sand used in the state of fluid mud to feed the blast-pipes is about as tine as flouremery. To make up the waste, a supply of sand tine enough to pass through asieve of one hundred and twenty wires to an inch is put into a hopper at the back end of the floor of the chamber 8, and gets gradually washed down into the mud-vessel.

The conical mud-vessel p is made of sheet metal, about two feet high and two feet in diameter at the top. In the center of its; cover is'a movable sieve, ten inches in diameter and about fourteen wires to the inch, to-catch any dirt. In the middle of the sieve is a tabulated opening, through which the suction-tubes ffv with fluid mud made about as thick as will flow freely through a tube of three-eighths of an inch in bore. The steam is immediately turned ou, and the fluid mud is sucked into the two blast-pipes a a, Fig. 4, and projected in two converging streams through the working-hole t into the chamber s. The workman lays the file k horizontally on the upper end of the feeler .r w, and. draws it slowly and regularly back and forward its whole length between the two sand -blasts, taking care to keep it level and straight between them, and turning it occasionally so as to test both sides on the fceler, until he finds that it is well sharpened in every part.

In order to have some lateral guide, it is convenient to adjust in front of the workinghole, about midway between the ends of the nozzle-tubes, a piece of smooth hard steel, 1', Fig. 5, in such a position that the workman can lightly touch it with the side of the tile. in its back and forward movements. The time required depends on the size of the file. the coarseness of its teeth. and their state ot'dnllness. and the workman is guided by the gradual improvement of the bite on the feeler. From this he also learns to judge whether the apparatus is working well, and whether the sand is of a proper fineness. Beyond a certain degree of fineness the sand does not cut so rapidly, though it will in timeproduce a smooth and keen edge. Coarse sand cuts rapidly, but makes a more rough and blunt edge. Under good conditions a twelve ineh fiat bastard file which has been fairly worn out by a fitter, but has not been used to clean castings, can be sharpened in about one to one and a half minute. The excess of water, carrying with it some of the finest mud, overflows from the mud-vessel into another box, where its solid matter settles.

Fig. 5 shows the sidewise inclination of the blast-pipes to the longitudinal axis of the tile, and also the lateral guide 1'.

We hereby disclaim anything that is de scribed in the patent granted-to B. U. Tilghman, dated October 18, 1870, No. 108,408; or in the patent granted to Milo A. Richardson, dated January 22, 1878, No. 199,573; orin the English patent granted to J. E. Mathewson, No. 1,584 of 1877.

What we claim as our invention, in sharpening files, rasps, and similar toothed tools by the sand blast, is-

1. 1n the method of sharpening files described, the employment of one or more interior steam-jets, combined with an exterior supply of fluid mud or fine sand mixed with water. applied to the sharpening of files, substantially as described.

2. In an apparatus for producing a wide and thin sand-blast, one or more thin apertures in the same plane, or. preferably a row of small holes having intervals between them for introducing the steam.

3. The improved method of sharpening the teeth of files. wherein the formation of grooves is avoided. by presenting the sand-blast at an acute angle sidcwise to the longitudinal axis of the tile, and at the same time at an acute angle to the horizontal plane of the teeth thereof, substantially as specified.

4. ln sharpening files by the sand-blast, the method of sharpenin gtwo adjacent sides simultaneously,which consists in presenting the file to a thin sand-blast of a width greater than that of the file and at the angle, substantially as described.

5. A feeler to test the progress of the sharpening during the operation.

6. The combination of a conical mud-vessel with the suction-pipe of a sand-blast apparatus. 

